Image quality test article set

ABSTRACT

Systems, methods, and apparatuses are provided for evaluating an image quality of an image produced by an x-ray computed tomography (CT) system.

RELATED APPLICATION

This application claims the benefit of International Patent ApplicationNo. PCT/US2015/052473, filed Sep. 25, 2015, entitled “IMAGE QUALITY TESTARTICLE”, which claims the benefit of U.S. Provisional PatentApplication 62/056,231, filed Sep. 26, 2014, entitled “IMAGE QUALITYTEST ARTICLE SET”, both of which are incorporated herein by reference intheir entirety.

TECHNICAL FIELD

The present application relates to a test article set comprising varioustest objects within each test article used to assess and evaluate theoverall image quality and other imaging-related metrics of imageproducing X-ray computed tomography (CT) security-screening systems

BACKGROUND

X-ray machine detection is commonly used for scanning containers,packages, parcels, and baggage (collectively referred to herein as“container(s)”) at airports, seaports, and border crossings and may beemployed for scanning mail and used by building security to scancontainers entering buildings. X-ray machines may be used to detectexplosives, drugs, or other contraband by analyzing a density of theitem(s) under examination, and x-ray capabilities may be furtherenhanced with computed tomography (CT) imaging technology. X-ray CTimaging technology uses a computer to process x-rays into one or moreslices of a specific area within a scanned container to allow an x-raytechnician to see inside the container without the need to otherwiseopen the container. Further computer processing may be used to generatea three-dimensional image of the inside of the container from a seriesof two-dimensional x-rays images. Software with a pre-loaded threatlibrary and graphical user interface (GUI) may be used to automate x-rayCT imaging to automatically detect threats and alert an x-ray technicianto possible threats within the container.

Regulators of x-ray CT systems may require a technical standard ortechnical specification to establish uniform engineering, methods,processes, and practices related to x-ray CT systems. The AmericanNational Standards Institute (ANSI) has accredited technical standardANSI N42.45-2011 for evaluating an image quality of x-ray CTsecurity-screening systems in a factory or original equipmentmanufacturer (OEM) environment. Performance testing of x-ray CT systemsfollowing the standard evaluates an x-ray CT system's ability to producean image of the container as well as the system software's ability toautomatically analyze image data to make a threat determination.

The present application is directed to novel test articles and methodsto evaluate the image quality of X-ray CT security-screening systems.

SUMMARY

In one embodiment, a system for assessing and evaluating an imageproducing x-ray computed tomography system containing a test object tobe scanned with x-rays to produce an image is provided, the system forassessing evaluating comprising: at least one test article, the at leastone test article configured to support one or more test objects withinan inner volume, the at least one test article comprising: (1) anexterior shell assembly surrounding an inner volume; (2) a base assemblycomprising a flat base portion; (3) a support structure comprising oneor more partitions configured to support one or more test objects, andone or more brackets configured to attach to at least one of: apartition and the flat base portion; wherein the exterior shell assemblyis configured to attach to the flat base portion of the base assemblysuch that the inner volume of the exterior shell assembly is bounded inpart by the flat base portion of the base assembly; and wherein the baseassembly is configured to attach to the exterior shell assembly, and theflat base portion is configured to support and attach to the supportstructure; and wherein the support structure is configured to attach tothe flat base portion of the base assembly and to be positioned withinthe inner volume of the exterior shell assembly.

In another embodiment, a system for assessing and evaluating an overallimage quality of an image producing x-ray computed tomography system,the system comprising: at least one test article, the at least one testarticle operable to support one or more test objects within an innervolume, the at least one test article further comprising: (1) anexterior shell assembly surrounding an inner volume and operable toattach to a base assembly; (2) a base assembly operable to attach asupport structure and operable to attach to the exterior shell assembly;and (3) a support structure within the inner volume operable to supportone or more test objects and operably attached to the base assembly;wherein the exterior shell assembly and the base assembly comprise acomposite structure, the composite structure further comprising a hollowcore structure, a resin matrix, and a reinforcement material, whereinthe hollow core structure is an open cell hexagonal honeycomb design ofpolypropylene material and of a thickness of about 0.20 inches, andfurther comprises a polyester scrim cloth barrier on each open side ofthe hollow core structure, the polyester scrim cloth barrierthermo-fused to the hollow core structure; wherein the reinforcementmaterial is a fiberglass cloth, the fiberglass cloth arranged in amulti-ply layering such that each ply of the multi-ply layering isarranged substantially orthogonal to a warp of an overlapping ply, eachply of the fiberglass cloth laminated to another ply of the fiberglasscloth by a resin matrix to form a multi-plied lamination, themulti-plied lamination of a ratio of about 70% fiberglass cloth to about30% resin matrix, wherein the multi-plied lamination is of a thicknessof about 0.018 inches; wherein the multi-plied lamination is furtherlaminated to each open side of the polyester scrim cloth covered hollowcore structure; wherein the exterior shell assembly and the baseassembly are formed by vacuum bag molding the composite structure;wherein at least one end of the exterior shell assembly comprises apolyhedral frustum; wherein the exterior shell assembly comprises atleast two handle assemblies extending into the inner volume, each handleassembly comprising a handle grip and a handle cup, the handle gripcomprising at least four ergonomic notches; and wherein the baseassembly and at least four corners of the exterior shell assembly arecoated with a two-part polyurethane flex coat spray.

In another embodiment, a resin matrix consisting essentially of amixture of the following materials in the proportions indicated isprovided, the resin matrix: (a) about 78.32% resin by weight; (b) about2.35% silicon dioxide by weight; (c) about 6.27% calcium carbonate byweight; (d) about 11.98% curing agent by weight; (e) about 0.29% darkblue dye by weight; (f) about 0.78% white dye by weight.

In another embodiment, a resin matrix consisting essentially of amixture of the following materials in the weights indicated is provided,the resin matrix: (a) about 400.0 grams resin; (b) about 12.0 gramssilicon dioxide; (c) about 32.0 grams calcium carbonate; (d) about 61.2grams curing agent; (e) about 1.5 grams dark blue dye; (f) about 4.0grams white dye.

In another embodiment, a dosimeter assembly for use in a x-ray computedtomography system test article is provided, the dosimeter assemblycomprising: a dosimeter shelf; an alignment bracket; a dosimeter window;an access panel; and a connection interface.

In another embodiment, an acetal cylinder assembly is provided, theacetal cylinder assembly comprising: two or more annular metal devices;two or more acetal cylinder forming sections of the cylinder assembly,each of which is configured to interconnect with another, wherein aportion of at least two of the acetal cylinder sections is undercut forone of the annular metal devices to fit over the undercut portion suchthat an annular metal device is sized to fit over the undercut portion.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying figures, which are incorporated in and constitute apart of the specification, illustrate various example systems andmethods, and are used merely to illustrate various example embodiments.

FIG. 1 illustrates example test articles and a storage/transport case.

FIG. 2A illustrates an example base assembly and support structure withtest objects.

FIG. 2B illustrates an example base assembly and support structure withtest objects.

FIG. 2C illustrates an example exterior shell assembly.

FIG. 3A illustrates a front view of an example exterior shell assembly.

FIG. 3B illustrates a rear view of an example exterior shell assembly.

FIG. 4A illustrates a perspective view of an example test articleassembly.

FIG. 4B illustrates an exploded view of an example test articleassembly.

FIG. 5 illustrates an exploded view of an example test article assembly.

FIG. 6 illustrates an exploded view of an example test object supportstructure.

FIG. 7A illustrates an example dosimeter assembly.

FIG. 7B illustrates an exploded view of an example dosimeter assembly.

FIG. 8 illustrates an example interconnection between a test article andan external computing device.

FIG. 9 illustrates an exploded view of an example test article assembly.

FIG. 10 illustrates an exploded view of an example test object supportstructure.

FIG. 11 illustrates a front view of an example exterior shell assembly.

FIG. 12 illustrates an example handle cover.

FIG. 13 illustrates an exploded view of an example test object.

FIG. 14 illustrates an exploded view of an example test object.

FIG. 15 illustrates an example hollow core structure.

FIG. 16 illustrates an example woven material.

FIG. 17 illustrates an example vacuum molding lay-up.

FIG. 18 illustrates an example molding tool.

FIG. 19 illustrates an example molding tool.

DESCRIPTION OF EMBODIMENTS

The American National Standards Institute (“ANSI”) has accreditedstandard ANSI 42.45-2011 (“the ANSI standard”) for evaluating an imagequality of x-ray computed tomography (CT) security-screening systems.While the ANSI standard establishes a test methodology and test objectsused to evaluate an image quality of an x-ray CT security-screeningsystem during performance testing of an x-ray CT security-screeningsystem, the ANSI standard leaves much to be desired for a test articleused to support test objects. As used herein, test article may bereferred to interchangeably as “a case,” “a test article,” “a chassis,”“a kit,” and “a phantom.”

The ANSI standard references use of an off the shelf plastic transitcase—specifically, Pelican™ Case model 1650-001-110 manufactured byPelican Products, Inc. of Torrance, Calif. The Pelican™ case specifiedin the standard is no longer manufactured and suitable replacements arenot readily available.

Moreover, use of the Pelican™ case presented many issues in evaluatingsecurity screening systems. First, the polypropylene outer caseconstruction of the Pelican™ case is heavy and thick and attenuates anx-ray beam of a security screening system under test. Attenuation of thex-ray beam negatively impacts evaluation of a security screeningsystem's image quality. Use of the polypropylene case material alsoadded to an overall weight of the Pelican case used in the ANSIstandard.

The ANSI standard also proposes removing structural support ridges fromthe Pelican™ case to reduce artifacts (i.e. errors andmisrepresentations) and noise in images produced from the Pelican™ casewhen used with a security screening system under test. Artifacts andnoise in an image negatively influence image quality metrics. However,removing the structural support ridges from the Pelican™ case alsoreduced an overall robustness and durability of the Pelican™ case.Removal of support ridges may also be a challenging endeavor.Additionally, because metal components may cause unwanted artifacts andnoise in an x-ray CT system image, the Pelican™ case had to have itsmetal hardware replaced with a plastic equivalent which is a tediousendeavor. The plastic hardware equivalent were often not as robust astheir metal equivalent. For example, acrylic pins used in hinges oftenbroke on account that the size and material of the pin could notwithstand the same rigors as the metal equivalent.

The ANSI standard also references an acrylic support system for use inthe Pelican case to support one or more test objects. The acrylicinterior support system not only added to the overall weight of each thePelican™ case, but was also easily damaged. Damage to the acrylicinterior support system often involved shattering of the acrylicinterior support system which would increase x-ray attenuation and causetest objects within the case to shift, both of which could negativelyinfluence image quality metrics.

Factory Acceptance Test System:

Embodiments claimed herein discloses a system for assessing andevaluating an overall image quality of an image producing x-ray CTsystem.

With reference to FIG. 1, a system 100 for performance testing an imageproducing x-ray CT system is illustrated. System 100 may include storageand transport case 102 as well as test article 104 a (phantom A) andtest article 104 b (phantom B). Storage and transport case 102 may beused to store test articles 104 a, 104 b when not in use. Use of storageand transport case 102 may protect test articles 104 a, 104 b fromenvironmental exposure and other potential damage which may affect anability of test articles 104 a, 104 b to properly evaluate an imageproducing x-ray CT system. An interior of storage and transport case 102may be lined with a padding or foam material (not shown) to furtherprotect test articles 104 a, 104 b from a negative interaction (i.e.bumping, rubbing, etc.) when inside storage and transport case 102.Further mechanical structures and supports may be used within transportcase 102 to properly orient and support test articles 104 a, 104 bwithin storage and transport case 102. Orientation, spacing, andpositioning of test objects within test articles 104 a, 104 b may be inaccordance with a technical specification or standard. Transport case102 may be sized and shaped to properly accommodate test articles 104 a,104 b so as to limit movement of test articles 104 a, 104 b withintransport case 102. Transport and storage case 102 may further includehardware such as: wheels to more easily facilitate movement of transportand storage case 102; bumpers and edge reinforcements to protectexternal surfaces of transport and storage case 102 from damage; andhandles, locks, and pulls to lift and secure transport and storage case102.

Exterior shell assembly 106 a of test article 104 a and exterior shellassembly 106 b of test article 104 b may be substantially similar inappearance and manufacture. Slight difference in exterior shell assembly106 a and 106 b may reflect different functions of test articles 104 aand 104 b. In one embodiment, test article 104 a is called “Phantom A”and a standard or specification specifies which test objects aresupported within test article 104 a. In another embodiment, test article104 b is called “Phantom B” and a standard or specification specifieswhich test objects are supported within test article 104 b. Exteriorshell assemblies 106 a and 106 b may be of a molded composite material.In a non-limiting embodiment, test articles 104 a and 104 b areapproximately 37 inches in length, by about 18 inches in length, andabout 10 inches in height.

With reference to FIGS. 2a and 2b , base assemblies 208 a and 208 b oftest articles 104 a and 104 b are respectively illustrated. Baseassemblies 208 a and 208 b may be of a molded composite material. Withreference to FIG. 2a , base assembly 208 a in conjunction with aninternal support structure 213 a of test article 104 a may supportvarious test objects 218 a, 218 b, 218 c, and 218 d. Base assembly 208 amay include a substantially flat base portion 210 with a raised lipportion 212 extending around a perimeter portion of base assembly 208 a.Raised lip portion 212 may include one or more through holes 224 tosupport a connection hardware (not shown) to connect exterior shellassembly 106 a to base assembly 208 a. Flat base portion 210 may supportone or more brackets 214 for attaching internal support structure 213 ato base assembly 208 a. Internal support structure 213 a may include oneor more partitions 216 to support test objects 218 a, 218 b, 218 c, and218 d. Various connection hardware (not shown) may secure: one or morebrackets 214 to flat base portion 210, one or more partitions 216 to oneor more brackets 214, and test objects 218 a, 218 b, 218 c, and 218 d toone or more partitions 216. Partitions 216 may be of a hard plastic suchas acrylonitrile butadiene styrene (ABS) or as specified by a technicalspecification or other technical standard.

In one embodiment, a standard or specification specifies that testobjects 218 a, 218 b, 218 c, and 218 d must be used in test article 104a. Test objects may be used for measuring a wide range of image qualityindicators.

Test object 218 a may be an acetal cylinder wrapped with layers ofaluminum, copper, tin, and lead, and imbedded with tungsten alloy pinsto conduct both effective atomic number (Z_(eff)) and CT valueuniformity and streak artifact test procedures. Effective atomic numberuniformity is a material property that represents an atomic number of atheoretical element that, if replaced by the actual element, wouldproduce the same x-ray attenuation characteristics. CT value is a valuereported by CT systems on a per voxel basis that is a function of amaterial's density and atomic number. The streak artifact test proceduremeasures an amount of streaks produced by metal pins in a plasticobject.

Test object 218 b may be a box of acetal and aluminum plates arranged toform a box with a diagonal acetal plate used for an image registrationtest procedure. Image registration test object 218 b may be used to testphysical alignment between imaging subsystem frames of reference.

Test object 218 c may be an acetal plate with a machined hole in eachend. Test object 218 c may be used to test object length accuracy.

Test object 218 d is an acetal triangle used to test path length CTvalue and Z_(eff). Acetal triangle test object 218 d measuresconsistency of density and Z_(eff) along a variable x-ray path length.

Flat base portion of 210 of base assembly 208 a may include access panel220 for access into an interior volume of test article 104 a whenexterior shell assembly 106 a is secured to base assembly 208 a.Alternatively, access panel 220 may be on exterior shell assembly 106 a.While test objects may be engineered, machined, and manufactured toexact tolerances, once test objects are arranged within an interiorvolume of test articles 104 a and 104 b to an exact arrangement (i.e.spatial coordinates) specified by a standard or specification, exteriorshell assembly 106 a may be secured to base assembly 208 a limitingaccess to an inner volume of test article 104 a. Access panel 220 mayprovide access to a portion of an inner volume separate from testobjects, for example, to access additional diagnostic equipment andmeasurement devices within an inner volume of test article 104 a.

Referring to FIG. 2b , base assembly 208 b similar to base assembly 208a described above, includes a flat base portion 210 that supports araised lip portion 212 and may have one or more bracket 214/partition216 assemblies affixed thereto to form an internal support structure 213b that may support various test objects 218 c, 218 e, and 218 f Internalsupport structure 213 b may include additional support hardware likecomponent support 217 used to support test object 212 f in anorientation specified by a technical standard or specification.

Test object 218 e may be an acetal cylinder used to test noiseequivalent quanta (NEQ) and CT value consistency. NEQ test object 218 emay provide an indication of image quality by providing in-plane specialresolution of a device under test normalized against noise. Test object218 e may also be used to test CT value consistency. CT valueconsistency test object 218 e may provide an indication of image qualityby providing an average CT value measurement and providing a variance ofCT values.

Test object 218 f may be an acetal rectangular bar presented at about 5°to measure a slice sensitivity profile (SSP). SSP test object 218 f mayprovide an indication of image quality by testing a resolution of animage in a same direction of a system's belt movement.

Both base assemblies 208 a and 208 b may be coated with a polyurethaneflex-coat spray to provide added protection and reinforcement to baseassemblies 208 a and 208 b. Polyurethane flex-coating of base assemblies208 a and 208 b may also provide additional traction for test articles104 a and 104 b when used on conveyor belt driven x-ray CT systems andprevent unwanted movement of test articles 104 a and 104 b about theconveyor belt which may negatively affect an evaluation of x-ray CTimaging systems. In one embodiment, exterior portions (i.e. portions notoperatively connected to an inner volume of test articles 104 a and 104b) of base assemblies 208 a and 208 b are sprayed with a polyurethaneflex-coat. In another embodiment, all of base assemblies 208 a and 208 bare sprayed with polyurethane flex-coat. In one embodiment, baseassemblies 208 a and 208 b may be molded from polyurethane.

With reference to FIG. 2c , an exterior shell assembly 206 isillustrated. Exterior shell assembly 206 may include brackets 219attached to an interior ceiling portion 221 of exterior shell assembly206. In one embodiment, brackets 219 are secured to an interior ceilingportion of exterior shell assembly 206 with an adhesive. Brackets 219may align with, and captivate partitions 216 on base assemblies 208 aand 208 b. Because of the unique position of brackets 216 on baseassemblies 208 a and 208 b, brackets 219 may be uniquely positionedwithin exterior shell assemblies 106 a and 106 b to align withcorresponding partitions 216 on base assemblies 208 a and 208 b.Brackets 219 may counteract an overturning moment of interior supportstructures 213 a and 213 b to keep interior support structures 213 a and213 b in place should test articles 104 a and 104 b be dropped.

Referring to FIGS. 3a and 3b , front and rear views of test article 104a are illustrated. Exterior shell assembly 106 a may attach to baseassembly raised lip portion 212 of base assembly 208 a. One or morethrough holes 224 may support connection hardware 326. As metalcomponents may have a negative effect on x-ray CT system image qualityand cause streaking, connective hardware components such as connectionhardware 326 may be of a plastic material. In one embodiment, connectionhardware 326 is a plastic rivet. In another embodiment, connectionhardware 326 is a plastic screw. Connection hardware 326 may be chosenbased on a desired function, for example plastic rivets may be used toprevent or limit exterior shell assembly 106 a from being removed frombase assembly 208 a to prevent access to an inner volume of testassembly 104 a and the test objects therein.

Exterior shell assembly 106 a may include a polyhedral frustum shapedfront end 328. Polyhedral frustum shaped front end 328 may be similar inshape to a truncated pyramid. The shape of front end 328 may assist testarticle 104 a in parting heavy curtains on conveyor belt driven x-ray CTsystems. Rear end 330 of exterior shell assembly 106 a may be of similarpolyhedral frustum shape. Both front end 328 and rear end 330 mayinclude a handle assembly 332.

Handle assembly 332 may be of an ergonomic design and includes handlecover 333 over a handle cup 335. Handle cup 335 may be secured toexterior shell assembly 106 a and extends into an inner volume of testarticle 104 a. Handle cup 335 may provide a recessed area for a user'sfingers to facilitate carrying of test articles 104 a. Handle cup 335may also prevent foreign objects or moisture from entering an innervolume of test article 104 a. A user may extend fingers through handlecover 333 and into handle cup 335 to facilitate carrying of test article104 a. Handle cover 333 may provide ergonomic notches that may matchcontours of a user's fingers. In one embodiment, handle cover 333 mayinclude interface 334 which may provide a wired or wireless connectionto other electrical devices such as diagnostic equipment and measurementdevices within an inner volume test article 104 a. Test articles 104 aand 104 b may include one or more handle assemblies 332.

Front end 328 may also include a window 336 for viewing a display ofdiagnostic equipment and measurement devices within an inner volume oftest article 104 a. In one embodiment, a dosimeter may be placed withinan inner volume of test article 104 a and used to measure a x-ray doseduring an evaluation of a x-ray CT imaging system. Window 336 may allowa technician to view a display of a dosimeter within an inner volume oftest article 104 a.

One or more corners of exterior shell assemblies 106 a and 106 b may becovered with a polyurethane flex-coat treatment or polyurethane cornerappliqué as a polyurethane corner protection 338 to reinforce andprotect corners of exterior shell assemblies 106 a and 106 b.Polyurethane corner protection 338 may be a polyurethane corner appliqué338 molded into shape. In one embodiment, polyurethane corner protection338 is a molded appliqué of another material coated with polyurethaneflex coat. In another embodiment, polyurethane corner protection 338 isa direct application of a polyurethane flex-coat spray to one or morecorners of exterior shell assemblies 106 a and 106 b.

Exterior shell assembly 106 a may also support various indicia 340thereon. Indicia 340 may be used to provide operating instructions andidentification for test article 104 a.

With reference to FIG. 4A, an example test article 404 a is illustrated.Test article 404 a may include a rectangular prism-shaped exterior shellassembly 406 a and a rectangular-shaped base assembly 408 a. Withreference to FIG. 4B an exploded view of test article 404 a showingrectangular prism-shaped exterior shell assembly 406 a andrectangular-shaped base assembly 408 a is shown.

With reference to FIG. 5, an exploded view of test article 104 a isillustrated. In addition to previously described components within aninner volume of test article 104 a, test article 104 a may also includedosimeter assembly 544. Dosimeter assembly 544 may include a dosimeterfor measuring X-radiation dosage. A display of dosimeter on dosimeterassembly 544 may be viewed through window 336. Access to dosimeterassembly 544, for example, to turn dosimeter on/off, change batteries,etc., may be through access panel 220 after access door 542 is removedfrom base assembly 208 a.

Referring to FIG. 6, an exploded view of internal support structure 213a is illustrated. Internal support structure 213 a may use one or morepartitions 216 and connection hardware 546 to support test objects 218a, 218 b, 218 c, and 218 d. Connection hardware 546 may be a variety ofinternally threaded and externally threaded components that connect toboth test objects 218 a, 218 b, 218 c, and 218 d and each other.Connection hardware 546 may be screws, standoffs, rods, rivets, washers,and the like. In one embodiment, connection hardware 546 may be of aplastic material that does not affect an x-ray CT system image. One ormore partitions 216 may have one or more through holes 548 for receivingconnection hardware 216. One or more partitions 216 may include cylindersupport hole 549 which receives a mounting extension on acetal cylinder218 a for support of acetal cylinder 218 a.

With reference to FIGS. 7a and 7b , an example dosimeter assembly 544 isillustrated. Dosimeter assembly 544 may include a dosimeter 750, one ormore components to form a dosimeter shelf 752, and through holes andblind holes (collectively “holes” 754) to receive dosimeter connectionhardware 756 to interconnect dosimeter assembly 744 components. In oneembodiment, dosimeter connection hardware 756 may be screws and washersoperable to interconnect one or more portions of dosimeter shelf 752. Inanother embodiment, dosimeter connection hardware 756 may be a cabletie/tie-wrap type fastener for securing dosimeter 750 to dosimeter shelf752. Alignment bracket 758 may be provided to provide proper alignmentof dosimeter 750 on dosimeter shelf 752. Alignment bracket 758 may beattached to shelf 752, with, for example, adhesive hardware 760.Dosimeter assembly 744 may be used with test articles 104 a and 104 b toprovide a proper positioning and secure arrangement of dosimeter 750within test articles 104 a and 104 b. For example, shelf 752 may bedesigned to provide for easy readability of a display on dosimeter 750through window 360. Design of shelf 752 may vary based on differentdosimeter types.

With reference to FIG. 8 an example interconnection between test article104 a and an external computing device 864 is illustrated. Test articles104 a or 104 b may have connection interfaces, such as interface 334,for connection to an external computing device 864. An interior volumeof test articles 104 a and 104 b may support instrumentation and otherelectrical devices that may connected to an external computing device864 via interface 334 to allow for two-way communication betweenexternal computing device 864 and instrumentation within an inner volumeof test articles 104 a and 104 b. In one embodiment, data from adosimeter 750 within an inner volume of test article 104 a is extractedto an external computing device 864 and dosimeter settings andparameters are controlled from an external computing device 864. Inanother embodiment, interface 334 is a universal serial bus (USB)connector that allows USB cord 862 to connect to interface 334.Interface 334 may provide a wired or wireless interface and may act as ahub to support a wired or wireless connection between one or moreexternal computing devices 864 and one or more instruments/electricaldevices within an inner volume of test articles 104 a and 104 b. In oneembodiment, an intermediary device, such as a wireless reader devicewiredly connects to interface 334 and wirelessly communicates withdosimeter 750. External computer device 864 may be any number ofprocessor driven devices such as a computer (laptop, desktop, etc.), atablet, a smart phone, and the like.

With reference to FIGS. 9 and 10 an exploded view of test article 102 band internal support structure 213 b including test objects 102 c, 102e, and 102 f are illustrated. As previously described, test article 104b may be similar to test article 104 a and may be adapted to supporttest objects 102 e, and 102 f that are not included in test article 104a. Likewise, internal support structure 213 b may be similar to internalsupport structure 213 a with partitions 116 and connection hardware 646.Cylinder support hole 549 on partitions 116 may be used to support testobject 102 e.

Referring to FIG. 11 an example front end 328 of a test article isillustrated. Front end 328 may have a handle assembly aperture 1166machined or molded therein to support handle assembly 332. Rear end 330may have a similar aperture to support handle assembly 332. Handle cup335 may extend into handle assembly aperture 1166 and be covered byhandle cover 333 to form handle assembly 332. A geometry of handleassembly aperture 1066 may vary based on handle assembly 332. In oneembodiment, notch 1166 a is part of handle assembly aperture 1166 toaccommodate extra functionality, such as hardware associated withinterface 334. In another embodiment, handle assembly aperture 1166 doesnot include notch 1166 a and is more circular in shape. Through holes1167 around handle assembly aperture 1166 may provide a connection pointto secure both of handle cover 333 and handle cup 335 (i.e. handleassembly 332) to a test article.

Referring to FIG. 12, an example handle cover 333 is illustrated. Handlecover 333 may include one or more ergonomic grooves 1268 that maycorrespond with a user's fingers and allow for a user's fingers toextend through handle cover 333 and into handle cup 335 to facilitatecarrying of a test article. Ergonomic grooves 1268 may allow a user tocarry test article using any phalanx portions of the finger, and mayallow a user's fingers to curl to provide a superior and ergonomic gripwhen carrying a test article. Handle cover holes 1270 disposed abouthandle cover 333 correspond to holes 1167 on an exterior shell assemblyto allow for a mechanical connection through holes 1270 and 1167 tosecure handle assembly 332 to an exterior shell assembly 106 a, 106 b.Connection hardware for securing handle assembly 332 to exterior shellassembly 106 a, 106 b may include screws, rivets, and the like.

Acetal Cylinder:

Acetal cylinder test object 218 a may be slightly redesigned from theANSI standard to address shortcomings not originally anticipated by theANSI standard while not departing from the specifications and purpose oftest object 218 a as described in the ANSI standard. Acetal cylindertest object 218 a may support one or more annular metal devices (rings)to test (Z_(eff)) and CT value uniformity on an x-ray CT system.

With reference to FIG. 13, an exploded view of an example acetalcylinder test object for measuring (Z_(eff)) and CT value uniformity isillustrated. Unlike previous designs specified by the ANSI standardwhere acetal cylinders were a one piece construct with metal ringsthereon, acetal cylinder test object 218 a may be divided into two ormore sections. In one embodiment, acetal cylinder test object 218 a isdivided into three sections—section 1372, 1374, and 1376. Sections 1372,1374, and 1376 may interconnect to one another via raised portions 1378and corresponding recesses (not shown) opposed to receive the raisedportions 1378. A complete assembly of acetal cylinder test object 218 amay be held together by partitions 216 on each side acetal cylinder testobject 218 a. Mounting protrusions 1382 on section 1372 and 1390 onsection 1376 may correspond with cylinder support holes 549 onpartitions 216 to hold acetal cylinder test object 218 a. A stricttolerance of a spacing between partitions 216 with cylinder supportholes 549 may be necessary to ensure section 1372, 1374, and 1376 remaincoupled as a complete assembly of acetal cylinder test object 218 a.Both mounting protrusions 1382 and 1390 may have hardware attachmentapertures therein, such as hardware attachment aperture 1392 to receiveconnection hardware 646 therein to securely connect, and mount acetalcylinder test object 218 a within internal support structure 213 a.

Tin foil ring 1386 and lead foil ring 1388 on section 1376 may beadhered to section 1376 with an adhesive or the like.

Acetal cylinder test object 218 a has been redesigned from the ANSIstandard to include multiple sections such as sections 1372 and 1374.Use of multiple sections 1372 and 1374 allow for a metal annular deviceto be easily added to sections 1372 and 1374 and securely held in placewhen sections 1372 and 1374 are joined with other sections (i.e. 1376)to form a complete assembly of acetal cylinder test object 218 a.

Prior to acetal cylinder test object design 218 a, the copper ring andaluminum ring of prior acetal cylinder test objects, due to thermalexpansion and contraction, would move about the acetal cylinder testobject, such that each ring would continually vary its position on theacetal cylinder and its spacing relative to other metal rings. Routinehandling of the prior test article would cause movement of the copperand aluminum rings. Movement of the copper and aluminum rings onprevious designs caused a problem because an exact spacing between themetal rings could not be maintained.

Section 1372 of acetal cylinder test object 218 a may include anundercut portion 1380 machined into a cylindrical shape to receive anannular metal device such as an aluminum ring. An aluminum ring may bemachined to a specific inner diameter (I.D.) and outer diameter (O.D.)such that aluminum ring may easily slide onto the cylindrical-shapedundercut portion 1380. Similarly, section 1374 may include undercutportion 1384 for receiving an annular metal device such as a copperring. A copper ring may be machined to specific dimensions to have aprecise (e.g. snug and fit) fitting over undercut portion 1384.Connection of section 1372 to section 1374 with an annular metal devicein place on undercut 1380 prevents movement of annual metal device abouta longitudinal axis of acetal cylinder test object 218 a. Similarly,connection of section 1374 to section 1376 while an annular metal deviceis in place on undercut 1384 prevents movement of annular metal deviceabout a longitudinal axis of acetal cylinder test object 218 a.Captivation of aluminum and copper rings prevents movement, and ensuresaccurate and repeatable results during image evaluation of an x-ray CTimage producing system.

Acetal cylinder test object 218 a may also be used as a streak artifacttest object. One or more blind holes 1394 may be machined into an end ofsection 1376 in a direction along a longitudinal axis of acetal cylindertest object 218 a. Blind holes 1394 may be used to support one or moremetal pin used in a streak artifact testing procedure. Layout, spacing,and depth of blind holes 1394 may be specified in accordance with atechnical standard or specification.

Referring to FIG. 14 an exploded view of an example acetal cylinder testobject 218 a is provided. Copper ring 1496 may be machined for a precisefit over undercut 1384 on section 1374 while aluminum ring 1497 may bemachined for a precise (e.g. snug or firm) fit over undercut 1380 onsection 1372. Tin foil ring 1386 may be held in place by an adhesive inlocation 1486 a on section 1376 while lead foil ring 1488 may be held inplace by an adhesive in location 1488 a on section 1376. Exact geometry,layout, spacing, positioning, and the like may be specified inaccordance with a technical standard or specification.

Metal pins 1498 may be inserted into blind holes 1394 for use in streakartifact testing procedures. In one embodiment, metals pins 1498 may betungsten or tungsten alloy pins.

Composite Structure:

One or more components of system 100 may be manufactured of a moldedcomposite. An advantage of using a molded composite over traditionalplastics and other materials, is that a molded composite may be of alower density than other materials to allow for a greater passage ofX-radiation through the composite, and thus less attenuation of theX-radiation compared to other materials. A greater passage ofX-radiation to an inner volume of test articles 104 a, 104 b to interactwith various test objects therein, provides for a better imageevaluation of an x-ray CT image producing system. A molded compositematerial may also reduce an overall weight of test articles 104 a, 104 bwhile also increasing a durability and robustness of 104 a, 104 b.

Molded composite material may be molded from a combination of a resinmatrix, a reinforcement material, and a hollow core structure. Withreference to FIG. 15, an open side view of an example hollow corestructure 1500 is illustrated. Hollow core structure may be a cellularstructure of component cells (cores) 1502 interconnected by cellularwalls 1504. Because a majority volume of cell 1502 is air, hollow corestructure 1500, as used in a molded composite, may reduce an overalldensity of a composite material while also decreasing an overall weightof composite material. Use of hollow core structure 1500 may also reduceattenuation of X-radiation. As used herein, an open side of hollow corestructure 1500 refers to each side of hollow core structure 1500 in aplane (xz plane) along a longitudinal axis (y-axis) for each cell. Inone embodiment, hollow core structure 1500 is an open cell hexagonalhoneycomb design of a polypropylene material. A thickness of hollow corestructure 1500 as measured between both open sides may be about 0.20inches thick. Thickness of walls 1504 may be about 0.005 inches. Apolyester scrim cloth 1506 may be thermally fused to walls 1504 on eachopen side of hollow core structure 1500 to cover both open sides ofhollow core structure to prevent an ingress of a resin matrix into cells1502 during a composite molding process.

A reinforcement material may be used with a resin matrix to form aportion of a molded composite. Reinforcement material may be a wovenmaterial such as fiberglass mat, Kevlar, carbon fiber, and the like. Inone embodiment, a reinforcement material may be a woven glass fibermaterial (i.e. fiberglass, fiberglass cloth). A combination of wovenglass fiber material with an epoxy-based resin matrix may be commonlyreferred to as fiberglass or glass reinforced plastic. Reinforcementmaterial may be chosen based on function, design, cost, and the like.For example, fiberglass mat may be used because of its costs, lowattenuation of X-radiation, and other properties which may makefiberglass mat suitable for use in a composite mold.

With reference to FIG. 16, an example woven glass fiber reinforcement(fiberglass cloth) 1608 is illustrated. Woven glass fiber reinforcementmaterial may be woven using different weave patterns including: plain,Dutch, basket, twill, satin, and like weave patterns. Typically, a weavepattern will include fibers running in a “warp” direction as indicatedby arrow 1610 and fibers running in a “weft,” “woof,” or “fill”direction as indicated by arrow 1612. Warp and fill fibers may begenerally orthogonal to each other. Glass reinforced plastic compositesmay be multi-plied constructions—that is, multiple layers of fiberglasscloth may be overlapped to form a composite structure. Each layer of afiberglass cloth may be a ply, such that a two-layer overlappingfiberglass cloth construction may be 2-ply construction, etc. In oneembodiment, each overlapping fiberglass cloth layer in a multi-pliedconstruction is in an opposite warp direction of an underlyingfiberglass cloth layer to maximize a unidirectional strength of anoverall assembly. Composite structures fabricated from glass reinforcedplastic may be fabricated in either of a hand lay-up or spray lay-upoperation.

Resin Matrix:

A resin matrix used in preparing molded composite components of system100 may use a special combination of materials to decrease a density ofthe resin matrix. Silicon dioxide (SiO₂) may be added to the resinmatrix to introduce micro-balloons into the matrix to further reduce thedensity of the matrix without compromising resin matrix strength.Similar to the effects of adding silicon dioxide to the resin matrix,calcium carbonate (CaCO₃) may also be added to the resin matrix tointroduce micro-balloons. An example resin matrix formula based on a 400gram batch is given in table 1.

TABLE 1 Resin Matrix Material Formula Description Weigh (grams) Resin400 Silicon Dioxide 12 Calcium Carbonate 32 Curing Agent 61.2 Dye (DarkBlue) 1.5 Dye (White) 4

Resin used in the resin matrix may be either a natural resin or asynthetic resin. In one embodiment, resin used in the resin matrix is anepoxy resin. In another embodiment, resin used in the resin matrix is abisphenol F epoxy resin. In another embodiment, resin used in the resinmatrix is a liquid epoxy resin manufactured from epichlorohydrin andbisphenol F. Resin used in the resin matrix may be a low viscosityliquid epoxy resin. Resin used in the resin matrix may have strongmechanical properties, and high temperature and chemical resistance. Acuring agent used in the resin matrix may be a co-reactant for resinused in the resin matrix to act as a hardener/curative. A curing agentused in the resin matrix may accelerate a resin matrix curing process.In one embodiment, a curing agent used in the resin matrix is a curingagent used to cure bisphenol F epoxy resins. In another embodiment, acuring agent used in the resin matrix is an amine. In anotherembodiment, a curing agent used in the resin matrix is an aliphaticamine. In another embodiment, a curing agent used in the resin matrix isliquid imidazole. Resin matrix may be oven cured at a temperature ofaround (160° F.-165° F.) at about one atmosphere (14.7 lb./in²) ofvacuum. Dyes may be added to the resin matrix formula to color the resinmatrix, and thus influence a final color of a molded and cured compositecomponent.

Method of Manufacture:

A composite used to manufacture exterior shell assemblies 106 a, 106 band base assemblies 208 a, 208 b of test articles 104 a, 104 b may befabricated of specific plies of fiberglass cloth laminated to both sidesof hollow core structure 1500 using a resin matrix. A laid-up compositemay be vacuum bagged and oven cured under vacuum. In one embodiment, aratio of 70% fiberglass cloth to 30% resin is used to provide a highstrength, lightweight, low density composite assembly. Each compositeassembly may comprise 2 inner plies and 2 outer plies of fiberglasscloth at a thickness of about 0.018 inches. Composite assemblies usingplies of this thickness may provide test articles 104 a, 104 b withample strength to endure a test environment while also reducing weightand attenuation of X-radiation. Artisan care during a composite lay-upprocess may be free of imperfections such as bridging, surface cracking,cloth wrinkle or gaps, resin starvation, etc. and may provide a smoothand/or textured surface free of pinholes. In corners of composite moldedstructures where hollow core structures 1500 meet, a thinner fiberglasscloth of about 0.010 inch thickness may be applied directly to a scrimcloth of each hollow core structure 1500 to prevent a resin matrix fromwicking into corner seams. Taking care to seal corners seams toeliminated both excess resin accumulation at corners, and thuseliminates potential high density area which may negatively affect imageevaluation of x-ray CT imaging systems. As mentioned previously, acomposite assembly of fiberglass cloth, hollow core, and resin matrixmay be oven cured at a temperature of around (160° F.-165° F.) at aboutone atmosphere (14.7 lb./in²) of vacuum. Molding parts under vacuum willsqueeze out all excess resin which may be captured (absorbed) in abreather/bleeder cloth within a vacuum bag during a molding process anddiscarded when a molding process is complete. Curing a compositeassembly at a specific heat under vacuum may provide a stable, uniformbond.

With reference to FIG. 17, an example composite lay-up on a mold 1714for vacuum molding is illustrated. A process of composite vacuum moldingmay comprise a mold 1716. Mold 1716 may be machined of a durablematerial such as aluminum and machined to precise tolerances to ensureuniform repeatability of composite molded components. A release agentmay be sprayed or applied on mold 1716 to ensure separation of acomposite assembly from mold 1716 at an end of a molding process.Exterior plies 1718 of fiberglass cloth/resin matrix combination may belaid-up against mold 1716 in a multi-plied construction as describedabove. Hollow core 1500 may be laminated to exterior plies 1718 and abreather/bleeder cloth 1722 may be placed on another open side of hollowcore 1500 to absorb excess resin matrix. Vacuum bag 1724 may enclosecomposite assembly and sealed at vacuum seal 1726. Composite assemblymay be oven cured at a specified temperature under vacuum. Vacuummolding of a composite assembly may include a complete layup and curingof an assembly or may require multiple lay-ups/curings to produce afinished composite assembly.

With reference to FIGS. 18 and 19 example molds 1828 and 1930 used tolay up composite molded parts are illustrated. Molds 1828 and 1930 maybe machined of a durable material to specifications and tolerancesspecified by a technical standard or specification. Molds 1828 and 1930may be of a durable material capable of withstanding multiple moldingswhile maintaining a specified tolerance. Molds 1828 and 1930 may be of adurable material or combination of durable materials to withstand vacuumand heat curing while maintaining a specified tolerance. In oneembodiment, portions of mold 1828 and 1930 are manufactured of metal andpolymeric materials. Molds 1828 and 1930 may have surface treatments(such as powder coating, machining, etc.) to emboss a surface patternonto a molded composite. In one embodiment, a Hammertone® powder coatingfinish is applied to molds 1828 and 1930 to emboss a Hammertone®appearance on composite molded parts.

Computer Evaluation Method:

A semi-automatic and/or automatic evaluation process may be developed toevaluate an image quality of x-ray CT security screening systems.

Given a limited number of security screening systems in the marketplace,centralized data libraries of image quality metrics and other metadatamay be accumulated to generate baseline data for each security screeningsystem.

If a security screening system passes a general test event whichincludes passing a system inspection and detection testing, imagequality (IQ) metrics in addition to image data, and other metadata maybe saved and stored at a centralized database location. Statisticalresults may also be recorded to a centralized database along withcorresponding IQ metrics, image data, and metadata.

IQ metrics, image data, and metadata may be catalogued into acentralized database and given a unique identifier. The IQ metrics andimage data may be analyzed by image analysis software with imageanalysis results being stored along with IQ metrics, image data, andmetadata in a centralized database. Cataloged IQ metrics, image data,and metadata in a centralized results database may be stored foradditional analysis and compared to existing data cataloged on acentralized results database. Statistical analysis of cataloged IQmetrics, image data, and meta data compared against baseline values mayprovide an indication of whether an image quality of a x-ray CT securityscreen system under test is within an acceptable range.

Search tools and graphical user interfaces (GUIs) analysis programs maybe incorporated with centralized results database to allow for rapid andaccurate specific queries of stored metadata. A GUI may be an IQanalysis tool that may provide for semi-automated or automatedextraction of metadata from image data files for cataloging and storagein a centralized database. A GUI may be programmed to auto-populatemetadata or allow for manual entry of metadata. A GUI may compareextracted metadata from a centralized database against a library ofbaseline metadata and use statistical analysis to determine whether animage quality (IQ) of a security screening system is within a passablerange.

Unless specifically stated to the contrary, the numerical parameters setforth in the specification, including the attached claims, areapproximations that may vary depending on the desired properties soughtto be obtained according to the exemplary embodiments. At the veryleast, and not as an attempt to limit the application of the doctrine ofequivalents to the scope of the claims, each numerical parameter shouldat least be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

Furthermore, while the systems, methods, and apparatuses have beenillustrated by describing example embodiments, and while the exampleembodiments have been described and illustrated in considerable detail,it is not the intention of the applicants to restrict, or in any waylimit, the scope of the appended claims to such detail. It is, ofcourse, not possible to describe every conceivable combination ofcomponents or methodologies for purposes of describing the systems,methods, and apparatuses. With the benefit of this application,additional advantages and modifications will readily appear to thoseskilled in the art. Therefore, the invention, in its broader aspects, isnot limited to the specific details and illustrative example andexemplary embodiments shown and described. Accordingly, departures maybe made from such details without departing from the spirit or scope ofthe general inventive concept. Thus, this application is intended toembrace alterations, modifications, and variations that fall within thescope of the appended claims. The preceding description is not meant tolimit the scope of the invention. Rather, the scope of the invention isto be determined by the appended claims and their equivalents.

As used in the specification and the claims, the singular forms “a,”“an,” and “the” include the plural. To the extent that the term“includes” or “including” is employed in the detailed description or theclaims, it is intended to be inclusive in a manner similar to the term“comprising,” as that term is interpreted when employed as atransitional word in a claim. Furthermore, to the extent that the term“or” is employed in the claims (e.g., A or B) it is intended to mean “Aor B or both.” When the applicants intend to indicate “only A or B, butnot both,” then the term “only A or B but not both” will be employed.Similarly, when the applicants intend to indicate “one and only one” ofA, B, or C, the applicants will employ the phrase “one and only one.”Thus, use of the term “or” herein is the inclusive, and not theexclusive use. See Bryan A. Garner, A Dictionary of Modern Legal Usage624 (2d. Ed. 1995). Also, to the extent that the terms “in” or “into”are used in the specification or the claims, it is intended toadditionally mean “on” or “onto.” To the extent that the term“selectively” is used in the specification or the claims, it is intendedto refer to a condition of a component wherein a user of the apparatusmay activate or deactivate the feature or function of the component asis necessary or desired in use of the apparatus. To the extent that theterm “operatively connected” is used in the specification or the claims,it is intended to mean that the identified components are connected in away to perform a designated function. Finally, where the term “about” isused in conjunction with a number, it is intended to include ±10% of thenumber. In other words, “about 10” may mean from 9 to 11.

1-48. (canceled)
 49. A dosimeter assembly for use in ax-ray computedtomography system test article, the dosimeter assembly comprising: adosimeter; a dosimeter shelf; an alignment bracket; a dosimeter window;an access panel; and a connection interface.
 50. The dosimeter assemblyof claim 49, wherein the dosimeter shelf is operable to be mountedwithin the x-ray computed tomography system test article.
 51. Thedosimeter assembly of claim 49, wherein a display of a dosimeter mountedon the dosimeter shelf within the x-ray computer tomography system testarticle is viewable through a dosimeter window on the x-ray computedtomography system test article.
 52. The dosimeter assembly of claim 49,wherein a dosimeter mounted on the dosimeter shelf within the x-raycomputer tomography system test article is accessible through the accesspanel on the x-ray computer tomography system test article.
 53. Thedosimeter assembly of claim 49, wherein the alignment bracket isoperably connected to the dosimeter shelf and operable to align adosimeter within the x-ray computer tomography system test article suchthat a dosimeter display is viewable through a dosimeter window on thex-ray computer tomography system test article.
 54. The dosimeterassembly of claim 49, wherein the connection interface is operablyconnected to a dosimeter within the x-ray computed tomography systemtest article.
 55. The dosimeter assembly of claim 54, wherein theconnection interface is wiredly connected to the dosimeter within thex-ray computed tomography system test article.
 56. The dosimeterassembly of claim 54, wherein the connection interface is wirelesslyconnected to the dosimeter within the x-ray computed tomography systemtest article.
 57. The dosimeter assembly of claim 49, wherein theconnection interface is on an outside surface of the x-ray computedtomography system test article and operably connected to a dosimeterwithin the x-ray computed tomography system test article.
 58. Thedosimeter assembly of claim 57, wherein the connection interface is aUSB plug.
 59. The dosimeter assembly of claim 49, wherein one or moreconnection hardware is used to interconnect different components of thedosimeter assembly. 60-64. (canceled)
 65. The dosimeter assembly ofclaim 49, wherein the alignment bracket provides a proper positioning ofthe dosimeter assembly relative to the x-ray computed tomography systemtest article.
 66. The dosimeter assembly of claim 49, wherein thedosimeter which measures x-ray dose is secured to the dosimeter shelf byone of: a cable tie/tiewrap and hardware screws.